Composition for functional layer of electrochemical element, functional layer for electrochemical element, laminate for electrochemical element, and electrochemical element

Abstract

The present invention provides a composition for electrochemical element functional layers, the composition being capable of forming a functional layer for electrochemical elements, the functional layer having excellent wet adhesion, while enabling an electrochemical element to exhibit high output characteristics. A composition for electrochemical element functional layers according to the present invention contains a particulate polymer which has a volume average particle diameter of 0.5 μm to 10 μm and a degree of swelling in an electrolyte solution of 120% or less.

Description

[Technical Field]

[0001] The present invention relates to a composition for an electrochemical element functional layer, a functional layer for an electrochemical element, a laminate for an electrochemical element, and an electrochemical element. [Background technology]

[0002] Electrochemical elements such as lithium-ion secondary batteries and electric double-layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, making them suitable for a wide range of applications.

[0003] Here, for example, a lithium-ion secondary battery generally includes battery components such as a positive electrode, a negative electrode, and a separator that isolates the positive electrode and the negative electrode to prevent a short circuit between them.

[0004] In recent years, further improvements to electrochemical element components such as positive electrodes, negative electrodes, and separators have been investigated with the aim of further enhancing the performance of lithium-ion secondary batteries. Specifically, attempts have been made to laminate layers (functional layers) that exhibit desired functions such as heat resistance and adhesiveness onto separator substrates and electrode substrates. Furthermore, from the perspective of improving the functional layer and further enhancing the performance of electrochemical elements such as lithium-ion secondary batteries, various studies have been conducted on functional layer compositions used in the formation of functional layers.

[0005] Specifically, as described in Patent Documents 1 and 2, for example, by using a particulate polymer with a swelling degree of 2 times or less relative to a non-aqueous electrolyte as a binder to be included in the functional layer composition, it is possible to suppress a decrease in the durability of the functional layer and suppress an increase in internal resistance, thereby improving the low-temperature output characteristics of the electrochemical element. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-185353 [Patent Document 2] Japanese Patent Publication No. 2017-084589 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the above-mentioned conventional functional layer compositions had room for improvement in terms of improving the adhesion of the functional layer after immersion in the electrolyte (hereinafter sometimes referred to as "wet adhesion") and enhancing the ion permeability of the functional layer to improve output characteristics.

[0008] Therefore, the present invention aims to provide an electrochemical element functional layer composition that has excellent wet adhesion properties and can form a functional layer for an electrochemical element that can exhibit high output characteristics in the electrochemical element. [Means for solving the problem]

[0009] The inventors diligently conducted research with the aim of solving the above problems. As a result, the inventors discovered that by using a composition for an electrochemical element functional layer containing a particulate polymer in which both the volume-average particle size and the degree of electrolyte swelling are within a predetermined range, it is possible to form an electrochemical element functional layer that has excellent wet adhesion and can enable the electrochemical element to exhibit high output characteristics, thus completing the present invention.

[0010] In other words, the present invention aims to advantageously solve the above problems, and the electrochemical element functional layer composition of the present invention is characterized by containing a particulate polymer having a volume-average particle diameter of 0.5 μm or more and 10 μm or less, and an electrolyte swelling degree of 120% or less. If a particulate polymer having the above-mentioned volume-average particle diameter and electrolyte swelling degree is contained, it is possible to form an electrochemical element functional layer that has excellent wet adhesion and can enable the electrochemical element to exhibit high output characteristics. In this invention, the "volume-average particle diameter" and the "electrolyte swelling degree" can be measured by the method described in the examples of this specification.

[0011] In this context, it is preferable that the particulate polymer in the electrochemical element functional layer composition of the present invention includes a hydrogenated polymer. Using a particulate polymer containing a hydrogenated polymer can further improve the wet adhesion of the functional layer and the output characteristics of the electrochemical element.

[0012] Furthermore, in the electrochemical element functional layer composition of the present invention, it is preferable that the hydrogenation rate of the hydrogenated polymer is 95% or higher. If the hydrogenation rate is 95% or higher, the degree of electrolyte swelling of the particulate polymer can be reduced, and the wet adhesion of the functional layer and the output characteristics of the electrochemical element can be further improved. In this invention, the "hydrogenation rate" is the hydrogenation rate for all carbon-carbon unsaturated bonds contained in the hydrogenated polymer (including double bonds in aromatic rings if the polymer has aromatic rings), and can be measured using nuclear magnetic resonance (NMR) spectroscopy.

[0013] Furthermore, the electrochemical element functional layer composition of the present invention preferably has a glass transition temperature of 0°C to 80°C of the particulate polymer. If the glass transition temperature of the particulate polymer is within the above range, the dry adhesion of the functional layer (the adhesion of the functional layer when not immersed in an electrolyte, which can affect the adhesion between battery components via the functional layer during the manufacturing process of the electrochemical element) can be improved, and the output characteristics of the electrochemical element can be further enhanced. In this invention, the "glass transition temperature" can be measured by the method described in the examples of this specification. Here, in this invention, when multiple glass transition temperatures are observed, such as when the particulate polymer is a block copolymer, the "glass transition temperature" refers to the value obtained by weighting the proportion of each structure that gives a glass transition temperature in the particulate polymer. Specifically, in the case of a block copolymer, the glass transition temperature can be calculated by weighting the glass transition temperatures of each block by the content of each block. More specifically, in the case of a block copolymer having block A and block B, the formula is: Glass transition temperature of the block copolymer = (Glass transition temperature of block A × Content of block A + Glass transition temperature of block B × Content of block B) / (Content of block A + Content of block B) It can be determined by

[0014] Furthermore, the composition for the functional layer of the electrochemical device of the present invention preferably further contains other polymers different from the particulate polymer. If other polymers are contained, it is possible to suppress the particulate polymer from dropping out of the functional layer.

[0015] And, in the composition for the functional layer of the electrochemical device of the present invention, the glass transition temperature of the other polymer is preferably lower than the glass transition temperature of the particulate polymer. If the glass transition temperature of the other polymer is lower than the glass transition temperature of the particulate polymer, the dry adhesiveness of the functional layer can be further enhanced.

[0016] Furthermore, the composition for the functional layer of the electrochemical device of the present invention preferably further contains non-conductive heat-resistant particles. If non-conductive heat-resistant particles are contained, a functional layer excellent in heat resistance can be formed, and the heat resistance of the electrochemical device can be enhanced.

[0017] Also, this invention aims to advantageously solve the above problems, and the functional layer for an electrochemical device of the present invention is characterized in that it is formed using any of the above-described compositions for the functional layer of the electrochemical device. The functional layer for an electrochemical device formed using the above-described composition for the functional layer of the electrochemical device is excellent in wet adhesiveness and can exhibit high output characteristics in the electrochemical device.

[0018] Furthermore, this invention aims to advantageously solve the above problems, and the laminate for an electrochemical device of the present invention is characterized in that the above-described functional layer for an electrochemical device is provided on one side or both sides of a substrate. The laminate for an electrochemical device provided with the above-described functional layer for an electrochemical device is excellent in wet adhesiveness and can exhibit high output characteristics in the electrochemical device, so it is suitable as an electrochemical device member.

[0019] Here, in the laminate for an electrochemical device of the present invention, the base material can be a separator base material. A laminate for an electrochemical device in which the base material is a separator base material can be suitably used as a separator of an electrochemical device.

[0020] And this invention aims to advantageously solve the above problems, and the electrochemical device of the present invention is characterized by including any one of the above-described laminates for an electrochemical device. An electrochemical device including the above-described laminate for an electrochemical device can exhibit high output characteristics and has a long life.

Effect of the Invention

[0021] According to the present invention, a functional layer for an electrochemical device having excellent wet adhesiveness and capable of exhibiting high output characteristics in an electrochemical device, and a composition for a functional layer for an electrochemical device capable of forming the functional layer for an electrochemical device are obtained. Also, according to the present invention, a laminate for an electrochemical device having excellent wet adhesiveness and capable of exhibiting high output characteristics in an electrochemical device is obtained. Furthermore, according to the present invention, an electrochemical device having high output characteristics and a long life is obtained.

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described in detail. Here, the composition for a functional layer for an electrochemical device of the present invention is used when forming the functional layer for an electrochemical device provided in the laminate for an electrochemical device of the present invention. And the laminate for an electrochemical device of the present invention includes a functional layer formed using the composition for a functional layer for an electrochemical device of the present invention. Also, the electrochemical device of the present invention includes at least the laminate for an electrochemical device of the present invention.

[0023] (Composition for Functional Layer for Electrochemical Device) The electrochemical element functional layer composition of the present invention contains a predetermined particulate polymer and may optionally further contain at least one selected from the group consisting of other polymers, non-conductive heat-resistant particles, other components, and a dispersion medium such as water. By using the functional layer composition of the present invention, it is possible to form an electrochemical element functional layer that has excellent wet adhesion and can enable the electrochemical element to exhibit high output characteristics.

[0024] <Particulate polymer> Here, the particulate polymer can function as a binder in the functional layer formed using the functional layer composition, and can exhibit good adhesive strength in particular after the functional layer has been immersed in the electrolyte. Furthermore, in this invention, the particulate polymer is required to have a volume-average particle diameter of 0.5 μm or more and 10 μm or less, and an electrolyte swelling degree of 120% or less. By keeping the electrolyte swelling degree of the particulate polymer low at 120% or less, swelling and softening when immersed in the electrolyte can be suppressed, allowing it to exert sufficient adhesive strength in the electrolyte and suppressing the decrease in ion permeability caused by the reduction of voids in the functional layer due to volume increase associated with swelling. In addition, if the volume-average particle diameter of the particulate polymer is 0.5 μm or more, both wet and dry adhesion can be improved. Moreover, if the volume-average particle diameter of the particulate polymer is 10 μm or less, detachment from the functional layer can be suppressed, and the particulate polymer can exert the desired function.Therefore, an electrochemical element equipped with a functional layer formed using the functional layer composition can exhibit high output characteristics, and deformation of the electrochemical element caused by the expansion and contraction of the electrode active material during charging and discharging can be suppressed, improving the capacity retention rate (extending the lifespan) of the electrochemical element after cycle testing.

[0025] [Volume-average particle diameter] Furthermore, the volume-average particle size of the particulate polymer is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of further improving the wet and dry adhesion of the functional layer, and is preferably 8 μm or less, more preferably 6 μm or less, from the viewpoint of further suppressing the shedding of the particulate polymer from the functional layer.

[0026] [Electrolyte swelling degree] Furthermore, the electrolyte swelling degree of the particulate polymer is preferably 115% or less, from the viewpoint of further improving the wet adhesion of the functional layer and further suppressing the decrease in the ion permeability of the functional layer. The electrolyte swelling degree of the particulate polymer is usually 100% or more, and preferably more than 100%.

[0027] [Glass transition temperature] Furthermore, the particulate polymer preferably has a glass transition temperature of 0°C or higher, more preferably 10°C or higher, even more preferably 30°C or higher, particularly preferably 50°C or higher, preferably 80°C or lower, and more preferably 70°C or lower. If the glass transition temperature of the particulate polymer is above the lower limit, deformation of the particulate polymer and reduction of voids in the functional layer can be suppressed, and the ion permeability of the functional layer can be ensured at a high level. Also, if the glass transition temperature of the particulate polymer is below the upper limit, the dry adhesion of the functional layer can be further improved.

[0028] [Types of polymers] Furthermore, the polymer constituting the particulate polymer is not particularly limited and may be a random polymer, a block polymer, or a hydride thereof (hydrogenated polymer). In particular, the polymer constituting the particulate polymer is preferably a hydrogenated polymer, more preferably a hydrogenated polymer with a hydrogenation rate of 95% or higher, and even more preferably a hydrogenated polymer with a hydrogenation rate of 98% or higher. If the polymer constituting the particulate polymer is a hydrogenated polymer, and especially a hydrogenated polymer with a hydrogenation rate of the above lower limit or higher, the degree of electrolyte swelling of the particulate polymer can be reduced, and the wet adhesion of the functional layer and the output characteristics of the electrochemical element can be further improved.

[0029] [Composition of polymer] Furthermore, the polymer constituting the particulate polymer is preferably a polymer having a cyclic hydrocarbon structure, and more preferably a polymer having a cyclic saturated hydrocarbon structure.

[0030] Here, the polymers having a cyclic saturated hydrocarbon structure are not particularly limited, and include, for example, polymers (addition polymers or ring-opening polymers) using cyclic olefin compounds as monomers and their hydrides, as well as hydrides of polymers using aromatic vinyl compounds as monomers. Among these, hydrides of ring-opening polymers using cyclic olefin compounds as monomers and hydrides of polymers using aromatic vinyl compounds as monomers are preferred.

[0031] The cyclic olefin compound is not particularly limited, but for example, Norbornene compounds, including unsubstituted or alkyl groups such as norbornene, 5-methylnorbornene, 5-ethylnorbornene, 5-butylnorbornene, 5-hexylnorbornene, 5-decylnorbornene, 5-cyclohexylnorbornene, and 5-cyclopentylnorbornene; norbornenes having alkenyl groups, such as 5-ethylidene norbornene, 5-vinyl norbornene, 5-propenyl norbornene, 5-cyclohexenyl norbornene, and 5-cyclopentenyl norbornene; Norbornenes containing aromatic rings, such as 5-phenylnorbornene; Norbornenes containing an oxygen atom and having a polar group, such as 5-methoxycarbonylnorbornene, 5-ethoxycarbonylnorbornene, 5-methyl-5-methoxycarbonylnorbornene, 5-methyl-5-ethoxycarbonylnorbornene, norbornenyl-2-methylpropionate, norbornenyl-2-methyloctanate, 5-hydroxymethylnorbornene, 5,6-di(hydroxymethyl)norbornene, 5,5-di(hydroxymethyl)norbornene, 5-hydroxy-i-propylnorbornene, 5,6-dicarboxynorbornene, and 5-methoxycarbonyl-6-carboxynorbornene; Norbornenes containing a nitrogen atom in a polar group, such as 5-cyanonorbornene; Dicyclopentadiene, methyldicyclopentadiene, tricyclo[5.2.1.0 2,6 Polycyclic norbornenes with three or more rings that do not contain aromatic ring structures such as deca-8-ene; Tetracyclo[9.2.1.0 2,10 .0 3,8 ] Tetradeca-3,5,7,12-tetraene (also known as 1,4-methano-1,4,4a,9a-tetrahydro-9H-fluorene), tetracyclo[10.2.1.0 2,11 .0 4,9 Polycyclic norbornenes with three or more aromatic rings, such as pentadeca-4,6,8,13-tetraene (also known as 1,4-methano-1,4,4a,9,9a,10-hexahydroanthracene); Tetracyclododecene, 8-methyltetracyclododecene, 8-ethyltetracyclododecene, 8-cyclohexyltetracyclododecene, 8-cyclopentyltetracyclododecene, 8-methoxycarbonyl-8-methyltetracyclo[4.4.0.1 2,5 .1 7,10 Tetracyclododecenes that are unsubstituted or have alkyl groups, such as ]-3-dodecene; Tetracyclododecenes having a double bond outside the ring, such as 8-methylidene tetracyclododecene, 8-ethylidene tetracyclododecene, 8-vinyl tetracyclododecene, 8-propenyl tetracyclododecene, 8-cyclohexenyl tetracyclododecene, 8-cyclopentenyl tetracyclododecene, etc.; Tetracyclododecenes having an aromatic ring, such as 8-phenyl tetracyclododecene; Tetracyclododecenes having a substituent containing an oxygen atom, such as 8-methoxycarbonyl tetracyclododecene, 8-methyl-8-methoxycarbonyl tetracyclododecene, 8-hydroxymethyl tetracyclododecene, 8-carboxy tetracyclododecene, tetracyclododecene-8,9-dicarboxylic acid, tetracyclododecene-8,9-dicarboxylic anhydride, etc.; Tetracyclododecenes having a substituent containing a nitrogen atom, such as 8-cyano tetracyclododecene, tetracyclododecene-8,9-dicarboxylic imide, etc.; Tetracyclododecenes having a substituent containing a halogen atom, such as 8-chloro tetracyclododecene; Tetracyclododecenes having a substituent containing a silicon atom, such as 8-trimethoxysilyl tetracyclododecene; Hexacycloheptadecenes such as Diels-Alder adducts of the above-mentioned tetracyclododecenes and cyclopentadiene; And so on.

[0032] Among them, as the cyclic olefin compound, a non-polar norbornene-based monomer is preferable, such as norbornenes having no substituent or an alkyl group (for example, norbornene, 8-ethyl tetracyclododecene), norbornenes having an alkenyl group (for example, ethylidene tetracyclododecene (8-ethylidene tetracyclododecene)), dicyclopentadiene, norbornene derivatives having an aromatic ring (for example, tetracyclo[9.2.1.0 2,10 .0 3,8Tetradeca-3,5,7,12-tetraene (also known as 1,4-methano-1,4,4a,9a-tetrahydro-9H-fluorene), unsubstituted or alkylated tetracyclododecenes (e.g., tetracyclododecene, 8-methoxycarbonyl-8-methyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene) is more preferable.

[0033] Furthermore, a polymer using a cyclic olefin compound as a monomer, which can be optionally hydrogenated, may be a polymer using only a cyclic olefin compound as a monomer, or a polymer using a cyclic olefin compound and a copolymerizable compound other than a cyclic olefin compound as a monomer, but it is preferable that the polymer uses only a cyclic olefin compound as a monomer.

[0034] Furthermore, polymers using cyclic olefin compounds as monomers, which can be optionally hydrogenated, are preferably polymers using tetracyclododecene, dicyclopentadiene, and norbornene as monomers, and more preferably ring-opened polymers using tetracyclododecene, dicyclopentadiene, and norbornene as monomers. Here, the proportion of structural units derived from tetracyclododecene in the polymer is preferably 15% by mass or more, more preferably 25% by mass or more, preferably 40% by mass or less, and more preferably 35% by mass or less. Furthermore, the proportion of structural units derived from dicyclopentadiene in the polymer is preferably 15% by mass or more, more preferably 25% by mass or more, preferably 40% by mass or less, and more preferably 35% by mass or less. Moreover, the proportion of structural units derived from norbornene in the polymer is preferably 30% by mass or more, more preferably 40% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less.

[0035] Furthermore, polymers using cyclic olefin compounds as monomers are not particularly limited and can be prepared, for example, by the methods described in Japanese Patent Publication No. 3235219 or Japanese Patent Publication No. 6590156.

[0036] Furthermore, aromatic vinyl compounds are not particularly limited, but include, for example, styrene; alkyl-substituted styrenes such as α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, and 5-t-butyl-2-methylstyrene; and halogen-substituted styrenes such as 4-chlorostyrene and 2,4-dichlorostyrene. Among these, styrene is preferred.

[0037] Furthermore, a polymer using an aromatic vinyl compound as a monomer may be a polymer using only an aromatic vinyl compound as a monomer, or a polymer using an aromatic vinyl compound and a copolymerizable compound other than an aromatic vinyl compound as monomers, but it is preferable that the polymer uses an aromatic vinyl compound and a copolymerizable compound other than an aromatic vinyl compound as monomers.

[0038] Furthermore, the polymer using an aromatic vinyl compound and a copolymerizable compound other than an aromatic vinyl compound as monomers may be a random polymer or a block polymer, but a block polymer is preferred.

[0039] Furthermore, copolymerizable compounds other than aromatic vinyl compounds include, without particular limitation, aliphatic conjugated diene compounds such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Among these, 1,3-butadiene and isoprene are preferred.

[0040] Furthermore, the proportion of structural units derived from aromatic vinyl compounds in the polymer is preferably 20% by mass or more, more preferably 25% by mass or more, preferably 60% by mass or less, and more preferably 40% by mass or less. In addition, the proportion of structural units derived from aliphatic conjugated diene compounds in the polymer is preferably 30% by mass or more, more preferably 50% by mass or more, preferably 80% by mass or less, and more preferably 75% by mass or less.

[0041] Furthermore, the hydrides of polymers using aromatic vinyl compounds and copolymerizable compounds other than aromatic vinyl compounds as monomers are not particularly limited and can be prepared, for example, by the method described in Japanese Patent Publication No. 6435733.

[0042] <Other polymers> Other polymers are polymers different from particulate polymers that can function as binders in functional layers formed using functional layer compositions.

[0043] [composition] Other polymers include known polymers used as binders, such as conjugated diene polymers, acrylic polymers, polyvinylidene fluoride (PVDF), and polyvinyl alcohol (PVOH). These other polymers may be used individually or in combination of two or more. Preferably, the other polymers are water-insoluble polymers that can be dispersed in a dispersion medium such as water, such as conjugated diene polymers, acrylic polymers, and polyvinylidene fluoride (PVDF). Conjugated diene polymers and acrylic polymers are more preferred, and acrylic polymers are even more preferred. When the functional layer is applied to the positive electrode surface of an electrochemical element, it is preferable that the other polymer is not a conjugated diene polymer. In this invention, a polymer is considered "water-insoluble" if, when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25°C, the insoluble content is 90% by mass or more.

[0044] Here, a conjugated diene polymer refers to a polymer containing conjugated diene monomer units. Specific examples of conjugated diene polymers are, without particular limitation, copolymers containing aromatic vinyl monomer units and aliphatic conjugated diene monomer units, such as styrene-butadiene copolymer (SBR), butadiene rubber (BR), acrylic rubber (NBR) (a copolymer containing acrylonitrile units and butadiene units), and their hydrides. Furthermore, acrylic polymers refer to polymers that contain (meth)acrylic acid ester monomer units. These other polymers may be used individually or in combination of two or more in any ratio.

[0045] Furthermore, other acrylic polymers that can be preferably used as polymers are not particularly limited, but include, for example, polymers containing crosslinkable monomer units, (meth)acrylic acid ester monomer units, and acidic group-containing monomer units.

[0046] The proportion of (meth)acrylic acid ester monomer units in the acrylic polymer is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 58% by mass or more, preferably 98% by mass or less, more preferably 97% by mass or less, and even more preferably 96% by mass or less. By setting the proportion of (meth)acrylic acid ester monomer units to be above the lower limit of the above range, the adhesion of the functional layer can be improved. Furthermore, by setting it to be below the upper limit, the electrochemical properties of the electrochemical element equipped with the functional layer can be further enhanced.

[0047] Furthermore, the proportion of crosslinkable monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, preferably 3.0% by mass or less, and more preferably 2.5% by mass or less. By setting the proportion of crosslinkable monomer units to or above the lower limit, the electrochemical properties of the electrochemical element equipped with the functional layer can be further enhanced. Also, by setting the proportion of crosslinkable monomer units to or below the upper limit, the adhesion of the functional layer can be improved.

[0048] Furthermore, the proportion of acid group-containing monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. By setting the proportion of acid group-containing monomer units to or above the lower limit, the dispersibility of other polymers in the functional layer composition and in the functional layer can be increased, and the electrochemical properties of the electrochemical element equipped with the functional layer can be sufficiently enhanced. Also, by setting the proportion of acid group-containing monomer units to or below the upper limit, the residual moisture content of the functional layer can be reduced, and the electrochemical properties of the electrochemical element can be sufficiently enhanced.

[0049] Furthermore, acrylic polymers may contain other monomer units.

[0050] [Glass transition temperature] The other polymers preferably have a glass transition temperature lower than that of the particulate polymer. If the glass transition temperature of the other polymers is lower than that of the particulate polymer, the dry adhesion of the functional layer can be further improved.

[0051] Furthermore, the glass transition temperature of the other polymers is preferably -100°C or higher, more preferably -90°C or higher, even more preferably -80°C or higher, preferably less than 30°C, more preferably 20°C or lower, and even more preferably 15°C or lower. If the glass transition temperature of the other polymers is above the lower limit, the dry adhesion and strength of the functional layer can be improved. On the other hand, if the glass transition temperature of the other polymers is below the upper limit, the flexibility of the functional layer can be improved.

[0052] [Content of other polymers] The content of other polymers is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the total of the non-conductive heat-resistant particles and particulate polymers described later. If the content of other polymers is above the lower limit above, it is possible to sufficiently prevent the particulate polymers and non-conductive heat-resistant particles from falling off the functional layer and to sufficiently improve the dry adhesion and wet adhesion of the functional layer. On the other hand, if the content of other polymers in the functional layer is below the upper limit above, it is possible to suppress the decrease in the ionic conductivity of the functional layer and suppress the decrease in the output characteristics of the electrochemical element.

[0053] Furthermore, other polymers are not particularly limited and can be prepared, for example, by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. Here, the proportion of each monomer in the monomer composition is usually the same as the proportion of each monomer unit in other polymers.

[0054] Furthermore, the polymerization method for other polymers is not particularly limited, and any method such as suspension polymerization, emulsion polymerization agglutination, or pulverization can be used. In addition, any polymerization reaction such as radical polymerization or living radical polymerization can be used.

[0055] Furthermore, the shape of the other polymers may be particulate or non-particulate, but from the viewpoint of effectively suppressing the shedding of components contained in the functional layer, it is preferable that the shape of the other polymers be particulate.

[0056] <Non-conductive heat-resistant particles> Here, the non-conductive heat-resistant particles are not particularly limited and include fine particles made of inorganic materials (i.e., inorganic fine particles) and fine particles made of organic materials (i.e., organic fine particles) that are stable and electrochemically stable in the operating environment of the electrochemical element. Furthermore, as non-conductive heat-resistant particles, inorganic fine particles and organic fine particles may be used individually, or inorganic fine particles and organic fine particles may be used in combination.

[0057] [Inorganic fine particles] Examples of inorganic fine particles include inorganic oxide particles such as aluminum oxide (alumina, Al2O3), aluminum oxide hydrate (boehmite, AlOOH), gibbsite (Al(OH)3), silicon dioxide, magnesium oxide (magnesia), magnesium hydroxide, calcium oxide, titanium dioxide (titania), barium titanate (BaTiO3), ZrO, and alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; covalent crystalline particles such as silicon and diamond; sparingly soluble ionic crystalline particles such as barium sulfate, calcium fluoride, and barium fluoride; and clay fine particles such as talc and montmorillonite. These particles may be subjected to elemental substitution, surface treatment, solid solution treatment, etc., as needed. Inorganic fine particles may be used individually or in combination of two or more types.

[0058] [Organic fine particles] Unlike the aforementioned particulate polymers and other polymers, organic microparticles are microparticles made of polymers that do not have adhesive properties. Examples of organic microparticles include various crosslinked polymer particles such as crosslinked polymethyl methacrylate, crosslinked polystyrene, crosslinked polydivinylbenzene, styrene-divinylbenzene copolymer crosslinked products, polystyrene, polyimide, polyamide, polyamideimide, melamine resin, phenol resin, and benzoguanamine-formaldehyde condensate; heat-resistant polymer particles such as polysulfone, polyacrylonitrile, polyaramid, polyacetal, and thermoplastic polyimide; modified and derivative products thereof; and heat-resistant organic particles disclosed in International Publication No. 2019 / 065416. Note that organic microparticles may be used individually or in combination of two or more types. As mentioned above, the organic fine particles are composed of polymers that do not have adhesive properties. Specifically, the glass transition temperature of the polymer constituting the organic fine particles is preferably 150°C or higher.

[0059] Among the non-conductive heat-resistant particles mentioned above, from the viewpoint of further improving heat resistance, inorganic fine particles and organic fine particles composed of polymers with a glass transition temperature of 150°C or higher are preferred, inorganic fine particles are more preferred, and particles made of alumina (alumina particles), particles made of boehmite (boehmite particles), particles made of barium sulfate (barium sulfate particles), and particles made of magnesium hydroxide (magnesium hydroxide particles) are even more preferred.

[0060] [Properties of non-conductive heat-resistant particles] The non-conductive heat-resistant particles preferably have a volume-average particle diameter of 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, preferably 1.0 μm or less, more preferably 0.9 μm or less, and even more preferably 0.8 μm or less. If the volume-average particle diameter of the non-conductive heat-resistant particles is 0.1 μm or more, it suppresses a decrease in the ionic conductivity of the functional layer due to excessive density packing of the non-conductive heat-resistant particles in the functional layer, allowing the electrochemical element to exhibit excellent output characteristics. On the other hand, if the volume-average particle diameter of the non-conductive heat-resistant particles is 1.0 μm or less, even if the functional layer is thinned, the electrochemical element member equipped with the functional layer can sufficiently exhibit excellent heat resistance. Therefore, it is possible to increase the capacitance of the electrochemical element while ensuring sufficient heat resistance of the electrochemical element member.

[0061] [Content of non-conductive heat-resistant particles] Furthermore, the amount of non-conductive heat-resistant particles in the functional layer composition is preferably such that the mixing ratio of non-conductive heat-resistant particles to particulate polymer is 1.2 times or more by volume (non-conductive heat-resistant particles / particulate polymer), more preferably 1.5 times or more, even more preferably 2.0 times or more, preferably 99 times or less, more preferably 20 times or less, even more preferably 15 times or less, and particularly preferably 10 times or less. If the mixing ratio of non-conductive heat-resistant particles to particulate polymer is within the above range by volume, a good balance between the heat resistance and adhesion of the functional layer is achieved.

[0062] <Other ingredients> The functional layer composition may contain any other components in addition to those described above. These other components are not particularly limited as long as they do not affect the electrochemical reactions in the electrochemical element, and include, for example, known additives such as dispersants, viscosity modifiers, and wetting agents. These other components may be used individually or in combination of two or more.

[0063] <Method for preparing compositions for functional layers of electrochemical elements> The method for preparing the functional layer composition is not particularly limited, and for example, it can be prepared by mixing the above-mentioned particulate polymer, other polymers, non-conductive heat-resistant particles, water as a dispersion medium, and other components. When particulate polymers or other polymers are prepared by polymerizing monomer compositions in an aqueous solvent, the particulate polymers or other polymers may be mixed directly with other components in an aqueous dispersion. Furthermore, when mixing particulate polymers or other polymers in an aqueous dispersion, the water in the aqueous dispersion may be used as the dispersion medium.

[0064] Here, the method of mixing the above-mentioned components is not particularly limited, but it is preferable to use a disperser as the mixing device in order to efficiently disperse each component. The disperser is preferably a device that can uniformly disperse and mix the above components. Examples of dispersers include ball mills, sand mills, pigment dispersers, grinders, ultrasonic dispersers, homogenizers, and planetary mixers.

[0065] Furthermore, prior to mixing the aforementioned particulate polymer with non-conductive heat-resistant particles and other polymers, it is preferable to pre-mix it with a dispersant such as a nonionic surfactant, anionic surfactant, cationic surfactant, or amphoteric surfactant. Among these, anionic surfactants can be suitably used as dispersants. Specific examples of anionic surfactants include sulfate ester salts of higher alcohols such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecyl sulfate, ammonium dodecyl sulfate, sodium octyl sulfate, sodium decyl sulfate, sodium tetradecyl sulfate, sodium hexadecyl sulfate, and sodium octadecyl sulfate; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, sodium laurylbenzenesulfonate, and sodium hexadecylbenzenesulfonate; and aliphatic sulfonates such as sodium lauryl sulfonate, sodium dodecylsulfonate, and sodium tetradecylsulfonate. Furthermore, the amount of dispersant added is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less, per 100 parts by mass of particulate polymer. If the amount of dispersant added is above the lower limit, the uneven distribution of particulate polymer in the functional layer can be suppressed, and the cycle characteristics of the resulting electrochemical element can be improved. If the amount of dispersant added is below the upper limit, the increase in the internal resistance of the resulting electrochemical element can be suppressed, and the deterioration of output characteristics can be suppressed.

[0066] (Functional layers for electrochemical elements and laminates for electrochemical elements) The functional layer for electrochemical elements of the present invention is formed using the functional layer composition described above. For example, it can be formed by applying the functional layer composition described above to the surface (one or both sides) of a suitable substrate to form a coating film, and then drying the formed coating film. That is, the functional layer for electrochemical elements consists of the dried product of the functional layer composition described above. The functional layer contains at least the particulate polymer described above, and optionally contains at least one more selected from the group consisting of other polymers, non-conductive heat-resistant particles, and other components. Each component contained in the functional layer is the same as that contained in the functional layer composition described above, and the preferred ratio of each component is the same as the preferred ratio of each component in the functional layer composition. Since the functional layer for electrochemical elements is formed using the functional layer composition described above, it has excellent wet adhesion and can improve the output characteristics of the electrochemical element obtained using such a functional layer. Furthermore, a laminate formed by forming the functional layer for electrochemical elements on one or both sides of a substrate can be used as the laminate for electrochemical elements of the present invention, and it has excellent wet adhesion and can improve the output characteristics of the electrochemical element.

[0067] <Base material> Here, there are no restrictions on the substrate to which the functional layer composition is applied. For example, a coating film of the functional layer composition may be formed on the surface of a release substrate, the coating film may be dried to form a functional layer, and the release substrate may be peeled off from the functional layer. In this way, the functional layer peeled off from the release substrate can also be used as a self-supporting film to form a component of an electrochemical element. However, from the viewpoint of improving the manufacturing efficiency of electrochemical element components by omitting the process of peeling off the functional layer, it is preferable to use a separator substrate or an electrode substrate as the base material. A laminate formed by forming a functional layer on one or both sides of a separator substrate can be used well as a separator with a functional layer, and a laminate formed by forming a functional layer on one or both sides of an electrode substrate can be used well as an electrode with a functional layer.

[0068] [Separator substrate] The separator substrate is not particularly limited, but known separator substrates such as organic separator substrates can be used. Organic separator substrates are porous members made of organic materials, and examples of organic separator substrates include microporous membranes or nonwoven fabrics containing polyethylene, polypropylene, polybutene, polyvinyl chloride, and other polyolefin resins, as well as aromatic polyamide resins. Among these, a microporous membrane made of polyolefin resin is preferred from the viewpoint that it is possible to increase the capacity per unit volume by increasing the ratio of electrode active material in the electrochemical element. The thickness of the separator substrate can be any thickness, preferably 5 μm to 30 μm, more preferably 5 μm to 20 μm, and even more preferably 5 μm to 18 μm.

[0069] [Electrode base material] The electrode substrate is not particularly limited, but examples include an electrode substrate in which an electrode composite layer containing electrode active material particles and a binder is formed on the current collector described above. Here, the electrode active material particles and binder contained in the electrode composite layer in the electrode substrate are not particularly limited, and any electrode active material particles and binder that can be used in the field of electrochemical elements can be used, for example, those described in Japanese Patent Application Publication No. 2013-145763 can be used. Furthermore, the current collector is made of a material that is electrically conductive and electrochemically durable. Specifically, the current collector can be made of, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. Among these, copper foil is particularly preferred as the current collector for the negative electrode. Also, aluminum foil is particularly preferred as the current collector for the positive electrode. Note that the above materials may be used individually or in combination of two or more materials in any ratio.

[0070] <Method for manufacturing functional layers and laminates> The method for manufacturing the functional layer and laminate of the present invention is not particularly limited, and for example, a method in which a functional layer is formed on a release sheet and the functional layer is transferred onto a substrate can be used. However, from the viewpoint of eliminating the need for a transfer and improving manufacturing efficiency, it is preferable to manufacture the laminate by a step of supplying a functional layer composition onto a substrate (supply step) and a step of drying the functional layer composition supplied onto the substrate (drying step).

[0071] [Supply process] In the supply process, the functional layer composition of the present invention described above is supplied onto a substrate to form a film of the functional layer composition on the substrate. The method of supplying the functional layer composition onto the substrate is not particularly limited; the functional layer composition may be applied to the surface of the substrate, or the substrate may be immersed in the functional layer composition. However, it is preferable to apply the functional layer composition to the surface of the substrate because it is easier to control the thickness of the manufactured functional layer. There are no particular limitations on the method for applying the functional layer composition to the surface of the substrate. Examples include the doctor blade method, reverse roll method, direct roll method, gravure coating method, bar coating method, extrusion method, and brush coating method. In the supply process, the functional layer composition may be formed on only one side of the substrate, or it may be formed on both sides of the substrate.

[0072] [Drying process] In the drying process, the film of the functional layer composition formed on the substrate in the supply process is dried to remove the dispersion medium and form the functional layer. The method for drying the coating of the functional layer composition is not particularly limited and known methods can be used, such as drying with hot air, hot air, or low-humidity air, vacuum drying, or drying by irradiation with infrared rays or electron beams. The drying conditions are not particularly limited, but the drying temperature is preferably 50 to 150°C and the drying time is preferably 1 to 30 minutes.

[0073] Furthermore, when manufacturing the laminate of the present invention, a functional layer may be formed on one side of the substrate by performing a supply process and a drying process, and then a functional layer may be formed on the other side of the substrate by performing a supply process and a drying process again.

[0074] Here, the thickness of the functional layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1 μm or more, preferably 6 μm or less, more preferably 5 μm or less, and even more preferably 3.5 μm or less. If the thickness of the functional layer is above the lower limit, the heat resistance of the functional layer will be extremely good. On the other hand, if the thickness of the functional layer is below the upper limit, the ion diffusion of the functional layer can be ensured, and the output characteristics of the electrochemical element can be further improved.

[0075] [Ratio of volume-average particle diameter of particulate polymer to thickness of functional layer] Furthermore, the ratio of the volume-average particle diameter of the particulate polymer to the thickness of the functional layer (volume-average particle diameter of the particulate polymer / thickness of the functional layer) is preferably 0.5 or more, more preferably 1.5 or more, preferably 10.0 or less, more preferably 9.0 or less, and even more preferably 8.0 or less. If the ratio of the volume-average particle diameter of the particulate polymer to the thickness of the functional layer is above the lower limit, the particulate polymer tends to protrude more easily from the surface in the thickness direction of the functional layer, thus enabling good wet adhesion. Also, if the ratio of the volume-average particle diameter of the particulate polymer to the thickness of the functional layer is below the upper limit, the number of adhesion points of the particulate polymer increases, thus enabling good adhesion.

[0076] (Electrochemical element) The electrochemical element of the present invention comprises an electrode and a separator, and is characterized in that at least one of the electrode and the separator, preferably the separator, comprises the laminate of the present invention described above. Because the electrochemical element of the present invention uses the laminate of the present invention described above as at least one of the electrochemical element material of the electrode and the separator, it has excellent output characteristics and can suppress deformation of the electrochemical element caused by the expansion and contraction of the electrode active material during charging and discharging, resulting in a long lifespan. In an electrochemical element using a laminate, the particulate polymer contained in the functional layer of the laminate may maintain its particulate shape or may be in any other arbitrary shape.

[0077] Furthermore, the electrochemical element of the present invention is not particularly limited, but includes, for example, a lithium-ion secondary battery, an electric double-layer capacitor, and a lithium-ion capacitor, and is preferably a lithium-ion secondary battery.

[0078] Hereinafter, we will describe a case in which a lithium-ion secondary battery is used as an example of the electrochemical element of the present invention, and the laminate of the present invention described above is used as the separator of the lithium-ion secondary battery. However, the electrochemical element of the present invention is not limited to this.

[0079] <Positive and negative electrodes> As the positive and negative electrodes, electrodes consisting of the known electrode substrates (positive electrode substrate and negative electrode substrate) described in the "Substrate" section can be used.

[0080] <Electrolyte> Typically, an organic electrolyte is used as the electrolyte, which is obtained by dissolving a supporting electrolyte in an organic solvent. For example, in lithium-ion secondary batteries, lithium salts are used as the supporting electrolyte. Examples of lithium salts include LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, and (C2F5SO2)NLi. Among these, LiPF6, LiClO4, and CF3SO3Li are preferred because they are easily soluble in the solvent and exhibit a high degree of dissociation. Note that one type of electrolyte may be used alone, or two or more types may be used in combination. Generally, the lithium ion conductivity tends to increase as the supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0081] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte. However, in lithium-ion secondary batteries, for example, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (ethyl methyl carbonate (EMC)), and vinylene carbonate; esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; and sulfur-containing compounds such as sulfolane and dimethyl sulfoxide are preferably used. A mixture of these solvents may also be used.

[0082] Among these, carbonates are preferred because they have a high dielectric constant and a wide stable potential range. Generally, lithium ion conductivity tends to increase as the viscosity of the solvent used decreases, so lithium ion conductivity can be adjusted by the type of solvent used. The concentration of the electrolyte in the electrolyte solution can be adjusted as appropriate. Furthermore, known additives may be added to the electrolyte solution.

[0083] <Method for manufacturing electrochemical elements> The method for manufacturing the electrochemical element of the present invention is not particularly limited. For example, a lithium-ion secondary battery, which is an example of the electrochemical element of the present invention as described above, can be manufactured by stacking a positive electrode and a negative electrode with a separator in between, winding or folding them as needed, placing them in a battery container, injecting an electrolyte into the battery container, and sealing it. At least one of the positive electrode, negative electrode, and separator is made of the laminate of the present invention. Furthermore, the battery container may optionally contain expanded metal, fuses, overcurrent prevention elements such as PTC elements, lead plates, etc., to prevent pressure rise inside the battery and overcharging / discharging. The shape of the battery may be any of the following: coin type, button type, sheet type, cylindrical type, prismatic type, flat type, etc. [Examples]

[0084] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" used to express quantities refer to mass unless otherwise specified. Furthermore, in polymers produced by copolymerizing multiple types of monomers, the proportion of a structural unit formed by polymerizing a certain monomer in the polymer is, unless otherwise specified, usually equal to the ratio of that particular monomer to the total monomers used in the polymerization of the polymer (the starting ratio). In the examples and comparative examples, various measurements and evaluations were carried out according to the following procedures.

[0085] <Electrolyte swelling degree> Particulate polymer was formed into a film approximately 0.1 mm thick, and this was cut into approximately 2 cm squares. The weight (weight before immersion) was measured. Then, it was immersed in an electrolyte solution at 60°C for 72 hours. The immersed film was removed, the electrolyte solution was wiped off, and the weight (weight after immersion) was measured immediately. The value of (weight after immersion) / (weight before immersion) × 100 (%) was defined as the degree of electrolyte swelling. The electrolyte solution used was a solution of ethylene carbonate and diethylene carbonate mixed solvent in a 1:1 (volume ratio) ratio with LiPF6 dissolved at a concentration of 1 mole / liter. <Volume-average particle size of polymers> The volume-average particle size of polymers (particulate polymers and binders (other polymers)) was measured by laser diffraction. Specifically, an aqueous dispersion solution containing the prepared polymer (adjusted to a solid content concentration of 0.1% by mass) was used as the sample. The volume-average particle size was defined as the particle size D50 at which the cumulative volume calculated from the smallest diameter side in the particle size distribution (volume-based) measured using a laser diffraction particle size distribution analyzer (Beckman Coulter, "LS-230"). <Glass transition temperature of polymers> A 10 mg sample was weighed into an aluminum pan, and a differential thermal analysis (DSC) curve was obtained. The measurement was performed using a differential thermal analysis instrument (EXSTAR DSC6220, manufactured by SII Nanotechnology Co., Ltd.) under the conditions specified in JIS Z8703, with an empty aluminum pan as a reference, and at a heating rate of 10 °C / min within the measurement temperature range of -100 °C to 500 °C. During this heating process, the glass transition temperature (°C) was determined by finding the intersection point between the baseline just before the endothermic peak of the DSC curve (where the differential signal (DDSC) is 0.05 mW / min / mg or higher) appears and the tangent line to the DSC curve at the first inflection point after the endothermic peak. In addition, since two glass transition temperatures were measured for the particulate polymer in Example 3, the following formula was used: Glass transition temperature = (Glass transition temperature derived from hydrogenated isoprene block × Content of hydrogenated isoprene block + Glass transition temperature derived from hydrogenated styrene block × Content of hydrogenated styrene block) / (Content of hydrogenated isoprene block + Content of hydrogenated styrene block) The value calculated using [the specified method] was defined as the glass transition temperature. <Hydrogenation rate of particulate polymers> Regarding the polymer before hydrogenation and the polymer after hydrogenation, 1 The amount of each carbon-carbon unsaturated bond was determined by measuring the 1H-NMR spectrum, and the hydrogenation rate (%) was calculated based on the difference in the amount of carbon-carbon unsaturated bonds before and after hydrogenation. 1 For 1H-NMR spectroscopy, o-dichlorobenzene was used as the solvent, and the JMN-AL series AL400 (manufactured by JEOL Corporation) was used as the NMR spectrometer. <Process adhesion (dry adhesion) of the functional layer> The fabricated positive electrode and functional layer-equipped separator were cut to a width of 10 mm and a length of 50 mm, stacked, and pressed using a roll press under the conditions of a temperature of 70°C, a load of 10 kN / m, and a press speed of 30 m / min to obtain an integrated product in which the positive electrode and functional layer-equipped separator were integrated. The resulting integrated material was placed with the positive electrode current collector side facing downwards, and cellophane tape was applied to the surface of the positive electrode. The cellophane tape used was that specified in JIS Z1522. The cellophane tape was fixed to a horizontal test stand. Then, the stress was measured when one end of the functional layer separator was pulled vertically upwards at a tensile speed of 50 mm / min and peeled off. Furthermore, the same procedure as when using the positive electrode was performed on the fabricated negative electrode, and the stress was measured. The stress measurements described above were performed 5 times each for the integrated positive electrode and functional layer separator, and for the integrated negative electrode and functional layer separator, for a total of 10 measurements. The average stress was calculated, and the resulting average value was defined as the peel strength (N / m). Then, using the calculated peel strength, the process adhesion between the electrode and the functional layer-equipped separator was evaluated according to the following criteria. A higher peel strength indicates higher process adhesion (adhesion of components during the battery manufacturing process). A: Peel strength of 6 N / m or more B: Peel strength is 4N / m or more and less than 6N / m C: Peel strength is 2N / m or more and less than 4N / m D: Peel strength less than 2N / m <Adhesion of the functional layer after immersion in electrolyte solution (wet adhesion)> A functional layer composition was applied to a separator substrate, and the functional layer composition on the separator substrate was dried at 50°C for 10 minutes to form a functional layer. A separator with this functional layer was used as the evaluation separator. The evaluation separator was cut into strips measuring 10 mm x 100 mm. Then, the separator was placed along the surface of the negative electrode composite layer on the negative electrode side via the functional layer, and then heated and pressed at 85°C and 0.5 MPa for 6 minutes to prepare a laminate comprising the negative electrode and the separator, and this laminate was used as the test specimen. The test specimen was placed in a laminate packaging with approximately 400 μl of electrolyte. After 1 hour, the test specimen, along with the laminate packaging, was pressed at 60°C and a pressure of 0.5 MPa for 15 minutes. After pressing, it was kept at 60°C for 1 day. The electrolyte used was a mixed solvent of EC, DEC, and vinylene carbonate (VC) (EC / DEC / VC (volume mixing ratio at 25°C) = 68.5 / 30 / 1.5), with LiPF6 dissolved at a concentration of 1 mol / L as the supporting electrolyte. Next, the test specimen was removed, and the electrolyte adhering to its surface was wiped off. Then, with the negative electrode current collector side of the specimen facing downwards, cellophane tape was applied to the negative electrode current collector side. The cellophane tape used was the type specified in JIS Z1522. The cellophane tape was fixed to a horizontal test stand. The stress was then measured when one end of the separator was pulled vertically upwards at a pulling speed of 50 mm / min to peel it off. This measurement was performed three times, and the average value of the stress was determined as the peel strength P2, which was evaluated according to the following criteria. A higher peel strength P2 indicates better adhesion of the functional layer in the electrolyte, and that the negative electrode and the separator with the functional layer are firmly bonded. A: Peel strength P2 is 4N / m or higher B: Peel strength P2 is 3N / m or more and less than 4N / m C: Peel strength P2 is 2N / m or more and less than 3N / m D: Peel strength P2 is less than 2N / m <Process Characteristics (Good Product Rate)> A total of 100 measurements were performed according to the method described in <Process Adhesion of Functional Layers (Dry Adhesion)> above. The number of samples with a peel strength of less than 1 N / m was counted and evaluated according to the following criteria. A lower number indicates a higher yield rate and superior process characteristics. A:0 pieces B: 1 or more but less than 3 C: 3 or more but less than 6 D: 6 or more <Output Characteristics> The fabricated lithium-ion secondary batteries were charged to 4.40V using constant current-constant voltage (CC-CV) charging in an atmosphere of 25°C to prepare the cells. The prepared cells were discharged to 3.0V using constant current methods at 0.2C and 3.0C, and their capacitance was determined. The discharge capacity retention rate, expressed as the ratio of capacitances (= (capacity at 3.0C / capacity at 0.2C) × 100 (%)), was then calculated. This measurement was performed on five lithium-ion secondary battery cells. The average discharge capacity retention rate for each cell was then calculated and evaluated according to the following criteria. A higher average discharge capacity retention rate indicates that the secondary battery has superior output characteristics. A: The average discharge capacity retention rate is 90% or higher. B: The average discharge capacity retention rate is between 85% and 90%. C: The average discharge capacity retention rate is 75% or more but less than 85%. D: Average discharge capacity retention rate is less than 75% <Cycle Characteristics> The fabricated lithium-ion secondary battery was left to stand at 25°C for 5 hours after electrolyte injection. Next, it was charged to a cell voltage of 3.65V using a constant current method at 25°C and 0.2C, and then subjected to an aging treatment at 60°C for 12 hours. Then, it was discharged to a cell voltage of 3.00V using a constant current method at 25°C and 0.2C. After that, CC-CV charging (upper limit cell voltage 4.40V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C. This charging and discharging at 0.2C was repeated three times. Subsequently, 100 charge-discharge cycles were performed in an environment of 25°C with a cell voltage of 4.40-3.00V and a charge-discharge rate of 1.5C. The discharge capacity of the first cycle was defined as X1, and the discharge capacity of the 100th cycle was defined as X2. Then, using the discharge capacities X1 and X2, the capacity retention rate ΔC' = (X2 / X1) × 100 (%) was calculated and evaluated according to the following criteria. A larger value for the capacity retention rate ΔC' indicates that the secondary battery has superior cycle characteristics and a longer lifespan. A: Capacity retention rate ΔC' is 93% or higher B: Capacity retention rate ΔC' is 90% or more but less than 93% C: Capacity retention rate ΔC' is 87% or more and less than 90% D: Capacity retention rate ΔC' is less than 87%

[0086] (Example 1) <Preparation of particulate polymer (A)> In a polymerization reactor that had been dried and purged with nitrogen, 2.0 parts of a monomer mixture consisting of 29% tetracyclododecene (TCD), 30% dicyclopentadiene (DCPD), and 41% norbornene (NB) (1% of the total amount of monomers used for polymerization), 785 parts of dehydrated cyclohexane, 1.21 parts of 1-hexene as a molecular weight modifier, 0.98 parts of an n-hexane solution of diethylaluminum ethoxide (concentration: 19%), and 11.7 parts of a toluene solution of tungsten (phenylimide) tetrachloride / tetrahydrofuran (concentration: 2.0%) were added, and the mixture was stirred at 50°C for 10 minutes. Next, the entire mixture was maintained at 50°C, and while stirring, 198.0 parts of the monomer mixture with the same composition as above were continuously added dropwise to the polymerization reactor over 150 minutes. After stirring was continued for 30 minutes following the completion of the dropwise addition, 4 parts of isopropyl alcohol were added to stop the polymerization reaction. When the polymerization reaction solution was measured by gas chromatography, the conversion rate of the monomers to polymers was 100%. Next, 300 parts of the resulting polymerization reaction solution were transferred to an autoclave equipped with a stirrer, and 32 parts of cyclohexane and 3.8 parts of diatomaceous earth-supported nickel catalyst (JGC Chemical Co., Ltd., "T8400RL", nickel load: 58%) were added. After purging the autoclave with hydrogen, the reaction was carried out at 190°C and under a hydrogen pressure of 4.5 MPa for 6 hours. After the hydrogenation reaction was complete, diatomaceous earth ("Radiolite® #500") was used as the filter bed, and the solution was filtered under pressure at 0.25 MPa using a pressure filter ("Funda Filter" manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd.) to obtain a colorless and transparent solution. To this solution, 0.5 parts of pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals, product name "Irganox® 1010") were added as an antioxidant per 100 parts of polymer hydride. Then, foreign matter was filtered out using a filter (manufactured by Quno Filters, "Zeta Plus® 30H", pore size: 0.5~1 μm) and a metal fiber filter (manufactured by Nichidai, pore size: 0.4 μm). Next, the filtrate obtained above was placed in a cylindrical concentrate dryer (manufactured by Hitachi, Ltd.) and, under conditions of a temperature of 290°C and a pressure of 1 kPa or less, the solvent cyclohexane and other volatile components were removed. The molten material was then extruded into strands from a die directly connected to the concentrate dryer, and after water cooling, it was cut with a pelletizer (manufactured by Nagata Seisakusho, "OSP-2") to obtain resin (A) pellets. The degree of electrolyte swelling, glass transition temperature, and hydrogenation rate of resin (A) were then measured. The results are shown in Table 1. Subsequently, 90 parts of cyclohexane and 10 parts of the resin (A) pellets obtained above were added to a container equipped with a stirrer, and the pellets were completely dissolved to obtain a resin solution. Furthermore, a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide was prepared by gradually adding an aqueous solution (A2) prepared by dissolving 2.8 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution (A1) prepared by dissolving 4.0 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring. Then, particulate polymer (A) was prepared by the dissolution suspension method. Specifically, the resin solution obtained as described above was added to the colloidal dispersion (A) containing magnesium hydroxide, and the mixture was further stirred to obtain a mixed solution. The obtained mixed solution was subjected to high-shear stirring at a rotation speed of 15,000 rpm for 1 minute using an in-line emulsifying disperser ("Cavitron" manufactured by Taiheiyo Kiko Co., Ltd.) to form droplets of the resin solution in the colloidal dispersion (A) containing magnesium hydroxide. Then, the colloidal dispersion (A) containing the above magnesium hydroxide was placed in a container equipped with a stirrer, and cyclohexane in the system was removed by heating and vacuum distillation to obtain an aqueous dispersion containing particulate polymer (A). Furthermore, while stirring the aqueous dispersion containing the above-mentioned particulate polymer (A), sulfuric acid was added dropwise at room temperature (25°C) and acid washing was performed until the pH was 6.5 or lower. Next, filtration separation was performed, and 500 parts of deionized water were added to the obtained solid to form a slurry again, and the water washing treatment (washing, filtration, and dewatering) was repeated several times. Then, filtration separation was performed, and the obtained solid was placed in a container of a drying oven and dried at 40°C for 48 hours to obtain dried particulate polymer (A). The particle size of the obtained particulate polymer (A) was measured. The results are shown in Table 1. <Preparation of an aqueous dispersion containing a binder (other polymers)> In a reactor equipped with a stirrer, 70 parts of deionized water, 0.15 parts of sodium lauryl sulfate (Kao Chemical Co., Ltd., "Emal® 2F") as an emulsifier, and 0.5 parts of ammonium persulfate as a polymerization initiator were supplied. The gas phase was replaced with nitrogen gas, and the temperature was raised to 60°C. Meanwhile, in a separate container, monomer composition (α) was prepared by mixing 50 parts of deionized water, 0.5 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 94 parts of n-butyl acrylate as a (meth)acrylic acid ester monomer, 2 parts of methacrylic acid as an acid group-containing monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, and 1 part of allyl methacrylate and 1 part of allyl glycidyl ether as crosslinkable monomers. The obtained monomer composition (α) was continuously added to a reactor equipped with the aforementioned stirrer over 4 hours to carry out polymerization. The reaction was carried out at 60°C during the addition. After the addition was completed, the reaction was further stirred at 70°C for 3 hours to terminate the reaction and obtain an aqueous dispersion containing particulate binder (α) as an acrylic polymer. The volume-average particle size and glass transition temperature of the obtained binder (α) were measured. The results are shown in Table 1. <Preparation of Slurry Composition> 100 parts of alumina (Sumitomo Chemical Co., Ltd., "AKP3000", volume average particle size: 0.7 μm) as inorganic fine particles were mixed with 0.5 parts of polyacrylic acid as a dispersant, and mixed using a ball mill. Then, 6 parts of an aqueous dispersion containing a binder (α) in terms of solid content and 1.5 parts of carboxymethylcellulose as a thickener (viscosity modifier) ​​were added, and deionized water was added to bring the solid content concentration to 55% to obtain the slurry before mixing. To 100 parts of particulate polymer (A), 0.2 parts of sodium dodecylbenzenesulfonate (Kao Chemical Co., Ltd., "Neoperex G-15") as an emulsifier were added and mixed to a solid content concentration of 20%. The resulting mixture was then added to the pre-mixed slurry obtained as described above. Deionized water was further added to achieve a solid content concentration of 40% to obtain a slurry composition (functional layer composition) in which the mixing ratio of inorganic particles (alumina) and particulate polymer (A) was as shown in Table 1. <Fabrication of separators with functional layers> A polyethylene microporous membrane (thickness: 12 μm) was prepared as a separator substrate. The slurry composition obtained as described above was applied to one side of this separator substrate using a bar coater method. Next, the separator substrate coated with the slurry composition was dried at 50°C for 1 minute to form a functional layer. The same operation was performed on the other side of the separator substrate to produce a separator with functional layers on both sides of the separator substrate. The thickness of each functional layer was set to 3.0 μm. <Fabrication of the positive electrode> 100 parts of LiCoO2 (volume-average particle size: 12 μm) as the positive electrode active material, 2 parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., "HS-100") as the conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Corporation, "#7208") in terms of solid content as the binder for the positive electrode composite layer, and N-methyl-2-pyrrolidone as the solvent were mixed to a total solid content concentration of 70%. These were mixed using a planetary mixer to prepare a slurry composition for the positive electrode. The above-mentioned slurry composition for the positive electrode was applied using a comma coater to a 20 μm thick aluminum foil, which would serve as the current collector, so that the film thickness after drying would be approximately 150 μm, and then dried. This drying was performed by transporting the aluminum foil at a speed of 0.5 m / min in a 60°C oven for 2 minutes. After that, it was heat-treated at 120°C for 2 minutes to obtain a positive electrode base roll before pressing. This positive electrode base roll before pressing was rolled using a roll press to obtain a pressed positive electrode having a positive electrode composite layer (thickness: 60 μm). <Fabrication of the negative electrode> In a 5 MPa pressure vessel equipped with a stirrer, 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of deionized water, and 0.5 parts of potassium persulfate as a polymerization initiator were added and thoroughly stirred. The mixture was then heated to 50°C to start polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a binder for the negative electrode composite layer (SBR). A 5% aqueous sodium hydroxide solution was added to this mixture containing the binder for the negative electrode composite layer to adjust the pH to 8, and unreacted monomers were removed by heated vacuum distillation. After that, the mixture was cooled to below 30°C to obtain an aqueous dispersion containing the desired binder for the negative electrode composite layer. 80 parts of artificial graphite (volume average particle size: 15.6 μm) as negative electrode active material (1) and 16 parts of silicon-based active material SiOx (volume average particle size: 4.9 μm) as negative electrode active material (2) were blended, and 2.5 parts of a 2% aqueous solution of carboxymethylcellulose sodium salt (manufactured by Nippon Paper Industries, "MAC350HC") as a viscosity modifier (in terms of solid content) and deionized water were added to adjust the solid content to 68%, and the mixture was further mixed at 25°C for 60 minutes. The solid content was further adjusted to 62% with deionized water, and the mixture was further mixed at 25°C for 15 minutes to obtain a mixture. To this mixture, 1.5 parts of an aqueous dispersion containing the above-mentioned binder for the negative electrode composite layer (in terms of solid content) and deionized water were added to adjust the final solid content to 52%, and the mixture was further mixed for 10 minutes to obtain a mixture. This mixture was defoamed under reduced pressure to obtain a smooth negative electrode slurry composition. The above-mentioned negative electrode slurry composition was applied using a comma coater onto a 20 μm thick copper foil, which served as the current collector, to a dry film thickness of approximately 150 μm, and then dried. This drying was performed by transporting the copper foil at a speed of 0.5 m / min in a 60°C oven for 2 minutes. After that, it was heat-treated at 120°C for 2 minutes to obtain a negative electrode base roll before pressing. This negative electrode base roll before pressing was rolled in a roll press to obtain a pressed negative electrode with a negative electrode composite layer (thickness: 80 μm). Then, using the functional layer-equipped separator, positive electrode, and negative electrode obtained as described above, dry adhesion, wet adhesion, and yield rate were evaluated. The results are shown in Table 1. <Manufacturing of lithium-ion secondary batteries> The pressed positive electrode prepared as described above was cut into a 49cm x 5cm rectangle and placed with the positive electrode composite layer side facing upwards. On top of the positive electrode composite layer, the functional layer separator, cut to 120cm x 5.5cm, was positioned so that the positive electrode was located on one side of the functional layer separator's longitudinal direction. Furthermore, the pressed negative electrode prepared as described above was cut into a 50cm x 5.2cm rectangle and placed on the functional layer separator so that the negative electrode composite layer side faced the functional layer separator, and the negative electrode was located on the other side of the functional layer separator's longitudinal direction. The resulting laminate was then wound using a winding machine to obtain a wound body. This wound material was pressed at 70°C and 1 MPa to flatten it, then wrapped in an aluminum packaging material to serve as the battery casing. The electrolyte (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate (volume ratio) = 68.5 / 30 / 1.5, electrolyte: 1 mol LiPF6) was injected, ensuring no air remained. The opening of the aluminum packaging material was then heat-sealed at 150°C to create a wound lithium-ion secondary battery with a capacity of 800 mAh. The output characteristics and cycle characteristics of the obtained lithium-ion secondary battery were evaluated. The results are shown in Table 1.

[0087] (Example 2) Particulate polymers, binders, slurry compositions, separators with functional layers, positive electrodes, negative electrodes, and lithium-ion secondary batteries were prepared in the same manner as in Example 1, except that particulate polymer (B), prepared in the same manner as particulate polymer (A), was used, except that particulate polymer (B) was prepared in the same manner as in Example 1, except that particulate polymer (A) was replaced with particulate polymer (B) prepared in the same manner as in Example 1, except that the monomer mixture composition was changed to tetracyclododecene (TCD) 22%, dicyclopentadiene (DCPD) 22%, and norbornene (NB) 56%. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0088] (Example 3) Except for using particulate polymer (C), which was prepared as described below, instead of particulate polymer (A), particulate polymer, binder, slurry composition, separator with functional layer, positive electrode, negative electrode, and lithium-ion secondary battery were prepared in the same manner as in Example 1. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of particulate polymer (C)> In a reactor equipped with a stirring device and thoroughly purged with nitrogen, 550 parts of dehydrated cyclohexane, 15.0 parts of dehydrated styrene, and 0.475 parts of n-dibutyl ether were added. While stirring the entire mixture at 60°C, 0.83 parts of n-butyllithium (15% cyclohexane solution) were added to initiate polymerization, and the reaction was continued for another 60 minutes while stirring at 60°C. The reaction mixture was measured by gas chromatography, and at this point, the polymerization conversion rate was 99.5%. Subsequently, 70.0 parts of dehydrated isoprene were added to the reaction mixture, and stirring was continued at 60°C for 30 minutes. When the reaction mixture was measured by gas chromatography, the polymerization conversion rate at this point was 99%. Subsequently, 15.0 parts of dehydrated styrene were added to the reaction mixture, and the entire mixture was stirred at 60°C for 60 minutes. Gas chromatography analysis of the reaction mixture revealed that the polymerization conversion rate at this point was approximately 100%. At this point, 0.5 parts of isopropyl alcohol were added to stop the reaction. Next, the polymer solution was transferred to a pressure reactor equipped with a stirring device, and 4.0 parts of diatomaceous earth-supported nickel catalyst (manufactured by JGC Catalysts & Chemicals, product name "E22U", nickel load: 60%) and 100 parts of dehydrated cyclohexane were added and mixed as hydrogenation catalysts. The reactor was then purged with hydrogen gas, and hydrogen was supplied while stirring the solution, and the hydrogenation reaction was carried out at a temperature of 170°C and a pressure of 4.5 MPa for 6 hours. The weight-average molecular weight (Mw) of the block copolymer hydride [D] obtained by the hydrogenation reaction was 52,500, and the molecular weight distribution (Mw / Mn) was 1.04. After the hydrogenation reaction was complete, the reaction solution was filtered to remove the hydrogenation catalyst. Then, 1.0 part of a xylene solution containing 0.05 parts of the phenol-based antioxidant pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Koyo Chemical Research Institute, Songnox1010) was added to the filtrate and dissolved. Next, the above solution was filtered through a ZetaPlus® filter 30H (manufactured by Cuno, pore size 0.5-1 μm), and then sequentially filtered through another metal fiber filter (manufactured by Nichidai, pore size 0.4 μm) to remove minute solid particles. Then, using a cylindrical concentrate dryer (manufactured by Hitachi, Ltd., Contro), the solvent cyclohexane, xylene, and other volatile components were removed from the solution at a temperature of 260°C and a pressure of 0.001 MPa or less. The molten material was extruded into strands from a die directly connected to the concentrate dryer, cooled, and then cut with a pelletizer to obtain 95 pellets of hydride block copolymer (styrene-isoprene-styrene block copolymer). The obtained block copolymer hydride had a weight-average molecular weight (Mw) of 51,900 and a molecular weight distribution (Mw / Mn) of 1.05. The electrolyte swelling degree, glass transition temperature, and hydrogenation rate of the block copolymer hydrides were then measured. The results are shown in Table 1. Two glass transition temperatures were observed: -50°C (derived from hydrogenated isoprene block) and 135°C (derived from hydrogenated styrene block). Subsequently, 90 parts of cyclohexane and 10 parts of the block copolymer hydride pellets obtained above were added to a container equipped with a stirrer, and the pellets were completely dissolved to obtain a resin solution. Furthermore, a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide was prepared by gradually adding an aqueous solution (A2) prepared by dissolving 2.8 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution (A1) prepared by dissolving 4.0 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring. Then, particulate polymer (C) was prepared by the dissolution suspension method. Specifically, the resin solution obtained as described above was added to the colloidal dispersion (C) containing magnesium hydroxide, and the mixture was further stirred to obtain a mixed solution. The obtained mixed solution was subjected to high-shear stirring at a rotation speed of 15,000 rpm for 1 minute using an in-line emulsifying disperser ("Cavitron" manufactured by Taiheiyo Kiko Co., Ltd.) to form droplets of the resin solution in the colloidal dispersion (A) containing magnesium hydroxide. Then, the colloidal dispersion (A) containing magnesium hydroxide was placed in a container equipped with a stirrer, and cyclohexane in the system was removed by heating and vacuum distillation to obtain an aqueous dispersion containing particulate polymer (C). Furthermore, while stirring the aqueous dispersion containing the above-mentioned particulate polymer (C), sulfuric acid was added dropwise at room temperature (25°C) and acid washing was performed until the pH was 6.5 or lower. Next, filtration separation was performed, and 500 parts of deionized water were added to the obtained solid to re-form a slurry, and the water washing treatment (washing, filtration, and dewatering) was repeated several times. Then, filtration separation was performed, and the obtained solid was placed in a container of a drying oven and dried at 40°C for 48 hours to obtain dried particulate polymer (C). The particle size of the obtained particulate polymer (C) was measured. The results are shown in Table 1.

[0089] (Example 4) In the preparation of the particulate polymer (A), 2.5 parts of sodium dodecylbenzenesulfonate were used instead of the colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide. The preparation of the slurry composition and the fabrication of the separator with a functional layer were carried out in the same manner as in Example 1, except that the particulate polymer, binder, slurry composition, separator with a functional layer, positive electrode, negative electrode, and lithium-ion secondary battery were prepared in the same manner as in Example 1. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Slurry Composition> [Preparation of heat-resistant slurry composition] 100 parts of alumina (Sumitomo Chemical Co., Ltd., "AKP3000", volume average particle size: 0.7 μm) as inorganic fine particles were mixed with 0.5 parts of polyacrylic acid as a dispersant, and mixed using a ball mill. Then, 6 parts of an aqueous dispersion containing a binder (α) in terms of solid content and 1.5 parts of carboxymethylcellulose as a thickener (viscosity modifier) ​​were added, and deionized water was added to bring the solid content concentration to 40% to obtain a heat-resistant layer slurry composition. [Preparation of adhesive layer slurry composition] 100 parts of particulate polymer were mixed with 20 parts of an aqueous dispersion containing a binder (α) in terms of solid content, and deionized water was added to obtain an adhesive layer slurry to achieve a solid content concentration of 5%. <Fabrication of separators with functional layers> A polyethylene microporous membrane (thickness: 12 μm) was prepared as a separator substrate. The heat-resistant layer slurry composition obtained as described above was applied to one side of this separator substrate by bar coating. Next, the separator substrate coated with the heat-resistant layer slurry composition was dried at 50°C for 1 minute to form a heat-resistant functional layer. Then, the adhesive layer slurry composition obtained as described above was applied by bar coating. Next, the separator substrate coated with the adhesive layer slurry composition was dried at 50°C for 1 minute to form an adhesive functional layer. The same procedure was performed on the other side of the separator substrate to produce a separator with functional layers, each having a heat-resistant functional layer and an adhesive functional layer on both sides of the separator substrate. The thickness of the heat-resistant functional layer in each functional layer was 3.0 μm, and the basis weight of the adhesive functional layer was 0.25 g / m². 2 That's what I decided.

[0090] (Comparative Example 1) Except for using particulate polymer (E), which was prepared as described below, instead of particulate polymer (A), particulate polymer, binder, slurry composition, separator with functional layer, positive electrode, negative electrode, and lithium-ion secondary battery were prepared in the same manner as in Example 1. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of particulate polymer (E)> A monomer composition was prepared by mixing 81 parts of styrene as an aromatic vinyl monomer, 16 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, and 3 parts of ethylene glycol dimethacrylate as a crosslinkable monomer. Furthermore, a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide was prepared by gradually adding an aqueous solution (A2) prepared by dissolving 5.6 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution (A1) prepared by dissolving 8.0 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring. A particulate polymer (A) was prepared by suspension polymerization. Specifically, the monomer composition obtained as described above was added to a colloidal dispersion (A) containing magnesium hydroxide, and after further stirring, 2.0 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, "Perbutyl® O") as a polymerization initiator was added to obtain a mixture. The obtained mixture was subjected to high-shear stirring at a rotation speed of 15,000 rpm for 1 minute using an in-line emulsifying disperser (manufactured by Taiheiyo Kiko Co., Ltd., "Cavitron") to form droplets of the monomer composition in the colloidal dispersion (A) containing magnesium hydroxide. Then, the colloidal dispersion (A) containing the above-mentioned magnesium hydroxide was placed in a reactor, and the temperature was raised to 90°C for 5 hours to carry out the polymerization reaction and obtain an aqueous dispersion containing particulate polymer (E). Furthermore, while stirring the aqueous dispersion containing the above-mentioned particulate polymer (E), sulfuric acid was added dropwise at room temperature (25°C) and acid washing was performed until the pH was 6.5 or lower. Next, filtration separation was performed, and 500 parts of deionized water were added to the obtained solid to re-form a slurry, and the water washing treatment (washing, filtration, and dewatering) was repeated several times. Then, filtration separation was performed, and the obtained solid was placed in a container of a drying oven and dried at 40°C for 48 hours to obtain dried particulate polymer (E). The particle size of the obtained particulate polymer (E) was measured. The results are shown in Table 1.

[0091] (Comparative Example 2) Except for using particulate polymer (F), which was prepared in the same manner as particulate polymer (A), except that the hydrogenation reaction time was changed to 3 hours instead of particulate polymer (A), particulate polymer, binder, slurry composition, separator with functional layer, positive electrode, negative electrode, and lithium-ion secondary battery were prepared in the same manner as in Example 1. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0092] (Comparative Example 3) Except for using 4.2 parts of sodium dodecylbenzenesulfonate, particulate polymers, binders, slurry compositions, separators with functional layers, positive electrodes, negative electrodes, and lithium-ion secondary batteries were prepared in the same manner as in Example 4. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0093] (Comparative Example 4) In the preparation of the particulate polymer (A), instead of using colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide, a colloidal dispersion (H) containing magnesium hydroxide as a metal hydroxide was used. This was prepared by gradually adding an aqueous solution (H2) prepared by dissolving 2.3 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution (H1) prepared by dissolving 3.3 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring. In the same manner as in Example 1, a particulate polymer, binder, slurry composition, separator with functional layer, positive electrode, negative electrode, and lithium-ion secondary battery were prepared. Various evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0094] [Table 1]

[0095] Table 1 shows that in Examples 1 to 4, functional layers for electrochemical elements can be obtained that exhibit excellent wet adhesion and high output characteristics for electrochemical elements. Furthermore, Comparative Examples 1 and 2 in Table 1 show that when the electrolyte swelling degree of the particulate polymer is large, the output characteristics decrease; Comparative Example 3 shows that when the volume average particle size of the particulate polymer is small, both wet adhesion and output characteristics decrease; and Comparative Example 4 shows that when the volume average particle size of the particulate polymer is large, both wet adhesion and cycle characteristics decrease. [Industrial applicability]

[0096] According to the present invention, a functional layer for an electrochemical element that exhibits excellent wet adhesion and high output characteristics for the electrochemical element, and a composition for an electrochemical element functional layer capable of forming said functional layer for an electrochemical element are obtained. Furthermore, according to the present invention, a laminate for electrochemical elements can be obtained that has excellent wet adhesion properties and can enable the electrochemical element to exhibit high output characteristics. Furthermore, according to the present invention, an electrochemical element with high output characteristics and a long lifespan can be obtained.

Claims

1. The particulate polymer has a volume-average particle diameter of 0.5 μm or more and 10 μm or less, and its electrolyte swelling degree is 120% or less when compared to an electrolyte solution consisting of a 1:1 (volume ratio) mixed solvent of ethylene carbonate and diethylene carbonate in which LiPF6 is dissolved at a concentration of 1 mole / liter. A composition for an electrochemical element functional layer, wherein the particulate polymer includes a hydrogenated polymer with a hydrogenation rate of 95% or more.

2. The electrochemical element functional layer composition according to claim 1, wherein the glass transition temperature of the particulate polymer is 0°C or higher and 80°C or lower.

3. The electrochemical element functional layer composition according to claim 1 or 2, further comprising another polymer different from the particulate polymer.

4. The electrochemical element functional layer composition according to claim 3, wherein the glass transition temperature of the other polymer is lower than the glass transition temperature of the particulate polymer.

5. A composition for an electrochemical element functional layer according to any one of claims 1 to 4, further comprising non-conductive heat-resistant particles.

6. A functional layer for an electrochemical element, formed using the composition for an electrochemical element functional layer described in any one of claims 1 to 5.

7. A laminate for an electrochemical element, comprising a functional layer for an electrochemical element as described in claim 6 on one or both sides of a substrate.

8. The laminate for an electrochemical element according to claim 7, wherein the substrate is a separator substrate.

9. An electrochemical element comprising a laminate for an electrochemical element according to claim 7 or 8.

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